1. Field of the Invention
The present invention relates to a floating type magnetic head having a magnetic conversion element provided in one end surface of a slider which is bonded and fixed to a tongue piece of a support mechanism. More particularly, the present invention relates to a floating type magnetic head apparatus which is capable of preventing a slider or the magnetic conversion element from being deformed by a bonding agent for bonding the slider.
2. Description of the Related Art
FIG. 10 is a side view illustrating a conventional example of a floating type magnetic head apparatus for use in a hard disk or the like. FIG. 11 is an exploded perspective view illustrating a slider and a core of the floating type magnetic head apparatus shown in FIG. 10. FIG. 12 is a bottom view illustrating a support mechanism in a state in which the slider is not mounted.
The floating type magnetic head apparatus shown in FIG. 10 comprises a slider 1, an I-shaped core 2, and a support mechanism for supporting the slider 1.
As shown in FIG. 11, protuberances 4 and 5 are monolithically molded at a front 1a of the slider 1. The I-shaped core 2 is bonded to the front end surfaces of the protuberances 4 and 5 by a bonding agent made of a non-magnetic substance such as a glass material. The joined portion of the protuberance 5 and the lower portion of the core 2 forms a gap G. As shown in FIG. 10, a coil C is wound around the core 2, and a groove 1b is formed at the front 1a of the slider 1. The space between the protuberance 4 and the protuberance 5, and the interior of the groove 1b serve as a space for winding the coil C.
Two rows of grooves 1c and 1c are formed on the lower surface of the slider 1 along the sliding movement of a disk. The two sides of the grooves 1c and 1c are formed into rail surfaces 1e, and a narrow rail surface 1f is formed in the boundary between the grooves 1c and 1c. Although the slider 1 floats slightly by an air flow above the disk when the disk rotates, the amount of floating of the gap G from the disk is adjusted to the most appropriate distance by the depth of the grooves 1c and 1c and the surface areas of the rail surfaces 1e and 1f.
As indicated by a dotted line, each of the rail surfaces 1e and 1f is formed into a nearly circumferential surface of a large radius which is curved along the sliding movement of the disk. The protuberance formed by the circumferential surface is generally called a crown. The dimension h of the protuberance in the central portion of the crown from the under surface of the slider is approximately 45 nm when the total length of the slider 1 is, for example, 2.8 mm. The provision of such a crown makes it possible to prevent the slider 1 from closely contacting the surface of the disk when the disk stops.
The support mechanism 13 shown in FIG. 12 comprises a mount 9 fixed to a head drive mechanism of a hard disk unit or the like, and a load beam 8 mounted in the mount 9. Both sides of the load beam 8 are formed of a plate spring of bent pieces 8a and 8a. A flexure 17 formed of a thin plate spring is mounted in the under surface of the tip portion of the load beam 8. A tongue piece 6 which is surrounded by a cutout 7b is integrally formed in the flexure 17, and the slider 1 is bonded and fixed to the tongue piece 6. As shown in FIG. 10, a spherical projection 10 protruding to a side opposite to the side on which the slider 1 is bonded, is formed in the nearly central portion of the tongue piece 6. The projection 10 is brought into contact with the lower surface of the load beam 8 so that it is pivotally supported.
A base portion 8b of the load beam 8 is able to be elastically deformed. The slider is pressed against the surface of the hard disk by a small force by an elastic force exhibited by the base portion 8b. The tongue piece 6 is able to move a little with the projection 10 as a fulcrum. With such a construction, it is possible for the lower surface of the slider 1 to follow a fluctuation of the disk surface.
In the floating type magnetic head apparatus, the slider 1 is bonded to the tongue piece 6 by a resin type bonding agent 11. Since the slider 1 is a very small part, the bonding agent 11 flows to the top surface of the tip portion 1d of the slider 1, or to the top surface of the protuberance 4 and sometimes further to the top surface 2a of the I-shaped core 2. Since the tip portion 1d of the slider 1 is liable to be deformed because the groove 1b is formed under the tip portion 1d, and the narrow protuberance 4 is more liable to be deformed. Therefore, if the bonding agent which flows to these portions is hardened, after which the hardened bonding agent expands or contracts due to a change in the temperature, the tip portion 1d of the slider 1 and also the protuberance 4 are deformed. Furthermore, if the bonding agent flows to the top surface 2a of the core 2, the core 2 is pressed or pulled in a direction in which it is deviated from the protuberance 4.
When, due to the above phenomenon, the gap G portion protrudes and shifts in the direction of the disk with respect to the lower surface of the slider 1, the gap between the gap G and the disk surface becomes too short when the slider 1 floats from the disk, problems occur, for example, the disk is damaged or the magnetic head is damaged. When, conversely, the gap G portion protrudes and shifts upward in the figure from the under surface of the slider 1, the gap between the gap G and the disk surface becomes too wide when the slider 1 floates from the disk, exerting an influence upon a recording or reproducing operation. Such a phenomenon becomes conspicuous as the amount of the bonding agent 11 which flows to the front of the slider 1 becomes larger. The above-described phenomenon becomes more conspicuous in a case in which the bonding agent flows to the top surface of the protuberance 4 than a case in which the bonding agent remains on the top surface of the tip portion 1d. In addition, when the bonding agent 11 flows to the top surface 2a of the I-shaped core 2 or to the side of the protuberance 4 and the I-shaped core 2, the phenomenon becomes conspicuous even more.
Also, the bonding area by the bonding agent 11 which is provided between the slider 1 and the tongue piece 6 must be an appropriate one. When the bonding area is too small, the bonding strength between the slider 1 and the tongue piece 6 decreases. However, if conversely the bonding area is too large, the slider 1 is given a bending stress due to the contraction or expansion of the hardened bonding agent, causing the protuberance dimension h in the center of the above-described crown to vary. This variation of h affects the amount of floating of the gap G from the disk.
Thus, it is conceivable that as shown in FIG. 13, a recess portion 1g extending along the width on the top surface of the slider 1, or as shown in FIG. 14, a recess portion 6a, is formed on the under surface of the tongue piece 6 so that the flow of the bonding agent 11 is prevented by the recess portion 1g or 6a in order to prevent the bonding agent 11 from flowing toward the top surface 2a of the core 2, and the bonding area is adjusted by the bonding agent 11.
However, since the slider 1 is formed of ferrite or the like, there is the possibility that the slider 1 may be damaged when the recess portion 1g is formed, and the operation for forming the recess portion 1g becomes complex. Also, since the tongue piece 6 is a thin plate member having a thickness of approximately 40 .mu.m, its strength decreases if the recess portion 6a is formed, the tongue piece must be etched to form the recess portion 6a, the forming operation is complicated, and the costs are increased.
In addition to the magnetic head shown in FIGS. 10 and 11, a bonding agent exerts an influence upon the magnetic head in which a magnetic conversion element is formed on one end surface of the slider by thin film formation technology.